The cord cutting event does look awfully risky when you see it on video but it's not significantly different to the risk associated with blowing the backshell\heatshield and the hundreds of other exquisitely choreographed events that are needed for any lander to get to the surface safely.

I agree. In Aerospace applications whenever You have a one-time event that absolutely has to work (typically escape or emergency systems) pyrotechnics are normally the system of choice. They are extremely reliable, degrade very slowly and act instantly.

they often have duplicate circuits for really critical pyrotechnics. Duplicate pyros, wiring, everything.

It's extraordinarily rare for pyros to fail to fire. Last time I remember that happening, they put one large sat on a ?Titan? built for two, and wired the spacecraft separation to the wrong pyro-lines. When the booster control sent the separation command, it went down the wires to the non-existent pyros to separate the nonexistant second sat.

That was the last one the Shuttle rescued before they stopped doing that sort of thing.

The cord cutting event does look awfully risky when you see it on video but it's not significantly different to the risk associated with blowing the backshell\heatshield and the hundreds of other exquisitely choreographed events that are needed for any lander to get to the surface safely.

Exactly. The MERs could have been killed by any number of other things too. Maybe the bolts wouldn't have blown to set the rovers free of the landers. Maybe the solar panel wings wouldn't have deployed, so the rovers would have been as good as dead anyway. All kinds of things can go wrong, many of which could end the mission before it begins. You just have to hope that everything goes as planned.

QUOTE (ustrax @ Nov 23 2006, 07:25 AM)

I'm sure that when the airbag idea appeared there were also comments regarding the lunacy of the idea... The time is to innovate and...roll!

I seem to recall something from a documentary about the MERs that was to this effect, that a lot of people thought that airbags would never stand a chance of working. So I think you're right.

This MSL EDL video was played tonight on stage at this Kobie Boykins presentation. It was fantastic. The video was longer and extended beyond the YouTube version to include more surface operations. It included a nice segment where the laser ablated a rock and an instrument recorded readings from the "smoke" wafting away and the hole in the rock. Spiffy demonstration.

The longer video also depicted a core sampling drill that could be used on rocks or on the "soil". The core sample (depicted from penetrating a rock) was slipped out of the bit and placed INTO the MSL for some unspecified analysis. Very cool. I hope the whole video makes it onto the web soon.

Kobie Boykins is a MER solar panel designer. Someone in the audience remarked that the MSL video showed no solar panels. He responded (paraphrased): "No. No solar panels. I'll let you speculate on what its power source is, since I'm not allowed to publicly discuss it yet."

The longer video also depicted a core sampling drill that could be used on rocks or on the "soil". The core sample (depicted from penetrating a rock) was slipped out of the bit and placed INTO the MSL for some unspecified analysis. Very cool. I hope the whole video makes it onto the web soon.

This MSL EDL video was played tonight on stage at this Kobie Boykins presentation. It was fantastic. The video was longer and extended beyond the YouTube version to include more surface operations. It included a nice segment where the laser ablated a rock and an instrument recorded readings from the "smoke" wafting away and the hole in the rock. Spiffy demonstration.

The longer video also depicted a core sampling drill that could be used on rocks or on the "soil". The core sample (depicted from penetrating a rock) was slipped out of the bit and placed INTO the MSL for some unspecified analysis. Very cool. I hope the whole video makes it onto the web soon.

Kobie Boykins is a MER solar panel designer. Someone in the audience remarked that the MSL video showed no solar panels. He responded (paraphrased): "No. No solar panels. I'll let you speculate on what its power source is, since I'm not allowed to publicly discuss it yet."

Laser sampling of a martian rock and core drilling by MSL are seen as part of the following Sky at Night extended Mars special. They may be from the same simulation as mentioned above and look pretty cool:

Upon seeing the MSL rover in simulations I'm always struck by just how scorpion-like the thing looks. That inclined rear RTG really gives it a sting in the tail and the whole thing looks quite menacing, like it'd eat Sojourner for breakfast!

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